• Authors:
    • Dejoux, J. F.
    • Aubinet, M.
    • Bernhofer, C.
    • Bodson, B.
    • Buchmann, N.
    • Carrara, A.
    • Cellier, P.
    • Di Tommasi, P.
    • Elbers, J. A.
    • Eugster, W.
    • Gruenwald, T.
    • Jacobs, C. M. J.
    • Jans, W. W. P.
    • Jones, M.
    • Kutsch, W.
    • Lanigan, G.
    • Magliulo, E.
    • Marloie, O.
    • Moors, E. J.
    • Moureaux, C.
    • Olioso, A.
    • Osborne, B.
    • Sanz, M. J.
    • Saunders, M.
    • Smith, P.
    • Soegaard, H.
    • Wattenbach, M.
    • Ceschia, E.
    • Beziat, P.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 139
  • Issue: 3
  • Year: 2010
  • Summary: The greenhouse gas budgets of 15 European crop sites covering a large climatic gradient and corresponding to 41 site-years were estimated. The sites included a wide range of management practices (organic and/or mineral fertilisation, tillage or ploughing, with or without straw removal, with or without irrigation, etc.) and were cultivated with 15 representative crop species common to Europe. At all sites, carbon inputs (organic fertilisation and seeds), carbon exports (harvest or fire) and net ecosystem production (NEP), measured with the eddy covariance technique, were calculated. The variability of the different terms and their relative contributions to the net ecosystem carbon budget (NECB) were analysed for all site-years, and the effect of management on NECB was assessed. To account for greenhouse gas (GHG) fluxes that were not directly measured on site, we estimated the emissions caused by field operations (EFO) for each site using emission factors from the literature. The EFO were added to the NECB to calculate the total GHG budget (GHGB) for a range of cropping systems and management regimes. N2O emissions were calculated following the IPCC (2007) guidelines, and CH4 emissions were estimated from the literature for the rice crop site only. At the other sites, CH4 emissions/oxidation were assumed to be negligible compared to other contributions to the net GHGB. Finally, we evaluated crop efficiencies (CE) in relation to global warming potential as the ratio of C exported from the field (yield) to the total GHGB. On average, NEP was negative (-284 +/- 228 gC m(-2) year(-1)), and most cropping systems behaved as atmospheric sinks, with sink strength generally increasing with the number of days of active vegetation. The NECB was, on average, 138 +/- 239 gC m(-2) year(-1), corresponding to an annual loss of about 2.6 +/- 4.5% of the soil organic C content, but with high uncertainty. Management strongly influenced the NECB, with organic fertilisation tending to lower the ecosystem carbon budget. On average, emissions caused by fertilisers (manufacturing, packaging, transport, storage and associated N2O emissions) represented close to 76% of EFO. The operation of machinery (use and maintenance) and the use of pesticides represented 9.7 and 1.6% of EFO, respectively. On average, the NEP (through uptake of CO2) represented 88% of the negative radiative forcing, and exported C represented 88% of the positive radiative forcing of a mean total GHGB of 203 +/- 253 gC-eq m(-2) year(-1). Finally, CE differed considerably among crops and according to management practices within a single crop. Because the CE was highly variable, it is not suitable at this stage for use as an emission factor for management recommendations, and more studies are needed to assess the effects of management on crop efficiency.
  • Authors:
    • Mary, B.
    • Laurent, F.
    • Aubrion, G.
    • Fontaine, A.
    • Kerveillant, P.
    • Beaudoin, N.
    • Constantin, J.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 135
  • Issue: 4
  • Year: 2010
  • Summary: Improved agricultural practices are encouraged to reduce nitrate leaching and greenhouse gas emissions. However, the effects of these practices are often studied at annual or rotation scale without considering their long-term impacts. We have evaluated the effects of catch crops (CC), no-till (NT) and reduced nitrogen fertilization (N-) on nitrogen fate in soil-plant system during 13-17 years in three experiments in Northern France. CC were present in all sites whereas tillage treatment and N fertilization rate were tested separately at one site. Crop biomass, N uptake and N leaching were monitored during the whole period. The N balance, i.e. the difference between N inputs and crop exportations, was only affected by fertilization rate whereas leached N varied with all techniques. CC was the most efficient technique to decrease N leaching (from 36 to 62%) and remained efficient on the long term. NT and N- had a positive but smaller impact. N storage in soil organic matter was markedly increased by CC (by 10-24 kg ha -1 yr -1), decreased by N- (-7.3 kg ha -1 yr -1) and not significantly affected by NT. The differences in gaseous N losses (denitrification+volatilization) between treatments were assessed by nitrogen mass balance. CC establishment had no significant effect on N gaseous emissions while NT increased them by 3.60.9 kg N ha -1 yr -1 and N- reduced them by 13.64.6 kg N ha -1 yr -1. Catch crops appear as a win/win technique with respect to nitrate leaching and C and N sequestration in soil.
  • Authors:
    • Risede,J. M.
    • Bouamer,S.
    • Petetin,C.
    • Lakhia,S.
    • Dorel,M.
  • Source: Fruits
  • Volume: 65
  • Issue: 2
  • Year: 2010
  • Summary: Introduction. In the French West Indies, farmers generally consider that periodical soil tillage is necessary to increase soil porosity and maintain high yield. However, in the non-tilled perennial banana plantations of the highlands, the soil exhibits better physical and biological properties than in the conventional banana plantations. To determine if tillage before banana planting is necessary for proper banana crop functioning and to assess the effect of tillage on soil quality, banana planting after conventional tillage was compared with no-till banana planting on crop residue mulch on an experimental plot. Materials and methods. Soil quality was assessed through indicators such as porosity, organic status, microbial biomass and structure of nematode communities. Crop functioning was assessed through plant growth, root distribution, and soil water and nitrogen availability. Results. We found that tillage reduced soil microbial biomass and the number of nematode functional guilds. Tillage had only a short-term effect on soil porosity and did not allow deeper extension of the root system. Although soil organic nitrogen mineralization was higher with conventional tillage, banana nitrogen nutrition was not better, probably because the high nitrogen fertilization offset the variations in availability of nitrogen from organic origin. We found that banana growth was better with no-till treatment. This could be explained by less drying out of soil due to the crop residue mulch left on the soil surface with no-till treatment. Conclusion. Relative to conventional tillage, no-till banana planting improved soil quality and crop performance.
  • Authors:
    • Schulze, E. D.
    • Houwelling, S.
    • Rivier, L.
    • Friedrich, R.
    • Scholz, Y.
    • Pregger, T.
    • Levin, I.
    • Piao, S. L.
    • Peylin, P.
    • Marland, G.
    • Paris, J. D.
    • Ciais, P.
  • Source: Global Change Biology
  • Volume: 16
  • Issue: 5
  • Year: 2010
  • Summary: We analyzed the magnitude, the trends and the uncertainties of fossil-fuel CO2 emissions in the European Union 25 member states (hereafter EU-25), based on emission inventories from energy-use statistics. The stability of emissions during the past decade at EU-25 scale masks decreasing trends in some regions, offset by increasing trends elsewhere. In the recent 4 years, the new Eastern EU-25 member states have experienced an increase in emissions, reversing after a decade-long decreasing trend. Mediterranean and Nordic countries have also experienced a strong acceleration in emissions. In Germany, France and United Kingdom, the stability of emissions is due to the decrease in the industry sector, offset by an increase in the transportation sector. When four different inventories models are compared, we show that the between-models uncertainty is as large as 19% of the mean for EU-25, and even bigger for individual countries. Accurate accounting for fossil CO2 emissions depends on a clear understanding of system boundaries, i.e. emitting activities included in the accounting. We found that the largest source of errors between inventories is the use of distinct systems boundaries (e.g. counting or not bunker fuels, cement manufacturing, non-energy products). Once these inconsistencies are corrected, the between-models uncertainty can be reduced down to 7% at EU-25 scale. The uncertainty of emissions at smaller spatial scales than the country scale was analyzed by comparing two emission maps based upon distinct economic and demographic activities. A number of spatial and temporal biases have been found among the two maps, indicating a significant increase in uncertainties when increasing the resolution at scales finer than ~200 km. At 100 km resolution, for example, the uncertainty of regional emissions is estimated to be 60 g C m-2 yr-1, up to 50% of the mean. The uncertainty on regional fossil-fuel CO2 fluxes to the atmosphere could be reduced by making accurate 14C measurements in atmospheric CO2, and by combining them with transport models.
  • Authors:
    • Petit, S.
    • Waldhardt, R.
    • Munier-Jolain, N.
    • Le Lagadec, L.
    • Meiss, H.
  • Source: Agriculture, Ecosystems & Environment
  • Volume: 138
  • Issue: 1-2
  • Year: 2010
  • Summary: Vegetation cover may affect weed seed predation by modifying the habitat quality for predatory organisms. Post-dispersal weed seed predation was measured by placing 'seed cards' in two perennial crops (alfalfa, cocksfoot) with and without crop cutting and in plots with bare soil. Each treatment was repeated four times in a randomized complete block design. Vegetation cover was measured by canopy light interception. Predation trials lasted two weeks and were repeated three times. Seed predation rates varied among three weed species (highest for Viola arvensis, intermediate for Alopecurus myosuroides, lowest for Sinapis arvensis). Vertebrate exclusion cages (12 mm x 12 mm openings) strongly reduced seed predation rates. Positive relationships were observed between vegetation cover and seed predation rates by both vertebrates and invertebrates for all weed species and trials, except when overall predation rates were very low. Predation rates were highest in uncut alfalfa, lowest on bare soil, but 16-64% of this variation could equally be explained by vegetation cover. The factorial design indicated that cutting had a stronger impact than crop species (legume or grass). Results suggest that weed seed predation may be enhanced by maintaining a high and temporally extended vegetation cover. (C) 2010 Elsevier B.V. All rights reserved.
  • Authors:
    • Riravololona, M.
    • Pardo, G.
    • Munier-Jolain, N. M.
  • Source: European Journal of Agronomy
  • Volume: 33
  • Issue: 1
  • Year: 2010
  • Summary: This study extends into the economic domain the analysis of a trial comparing cropping system prototypes based on the principles of Integrated Weed Management (IWM), which demonstrated their potential for managing weed infestations. A farm simulation model was used to analyse the consequences of implementing such IWM-based cropping systems at the farm scale. The labour requirement for field operations and their distribution over the year were compared to the amount of time when field conditions were suitable for the corresponding equipments. In the simulated IWM-based virtual farms, repeated shallow soil cultivations for promoting pre-sowing weed emergence and mechanical weeding could both be accommodated during suitable periods, but the rule of late cereal sowings for escaping periods of peak weed emergence generated possible labour bottlenecks. Machinery costs were calculated from the farm simulations so that the economic profitability of the virtual farms could be compared. In the economic context of 2006, the saving of input costs did not offset low yields of spring crops introduced in the crop sequence for diversifying sowing dates as required by IWM principles. The method of farm simulations could be used with other data sets from cropping system experiments to provide the required knowledge for supporting future policy development in Europe. (C) 2010 Elsevier B.V. All rights reserved.
  • Authors:
    • Saulas, P.
    • Ghiloufi, M.
    • Picard, D.
    • de Tourdonnet, S.
  • Source: Field Crops Research
  • Volume: 115
  • Issue: 1
  • Year: 2010
  • Summary: The sustainability of cropping systems can be increased by introducing a cover crop, provided that the cover crop does not reduce the cash crop yield through competition. The cover crop may be sown at the same time as a cash crop in the crop rotation. We carried out an experiment in 1999-2000 and 2000-2001 in the Paris Basin, to analyze the effects of simultaneously sowing winter wheat (Triticum aestivum L.) and red fescue (Festuca rubra L.), a turf grass. Competition between wheat and fescue was analyzed with one variety of red fescue, Sunset, and two varieties of wheat, Isengrain and Scipion, each sown at a density of 150 plants m(-2). In this study, we evaluated the effect of undersown fescue on wheat yield and analyzed the competition between the two species in detail. The undersown red fescue decreased wheat yield by about 12% for Isengrain (8.7 t ha(-1) for undersown Isengrain versus 9.8 t ha(-1) for Isengrain alone) and 7% for Scipion (7.4 t ha(-1) for undersown Scipion versus 8.0 t ha(-1) for Scipion alone). During the early stages of wheat growth (up to the '1 cm ear' stage, corresponding to stage 30 on Zadoks' scale), undersown fescue and fescue sown alone grew similarly. However, fescue biomass levels were much lower (5.6 and 4.7 g m(-2) for fescue grown alone and undersown fescue) than wheat biomass levels on the undersown plots (1120 g m(-2) for Isengrain and 111 g m(-2) for Scipion). From the e1 stage onwards, the wheat canopy rapidly extended, whereas that of red fescue remained sparse. The time lag between the beginning of the rapid increase in LAI and PAR interception by wheat grown alone and that for fescue grown alone was 590 dd in the second year. This resulted in much slower growth rates for undersown fescue than for undersown wheat. Biomass production rate was therefore low for undersown fescue (12% those of fescue grown alone, on average, at the time of wheat harvest), as were levels of water and nitrogen use. Neither the water deficit that occurred during the second experiment nor the nitrogen nutrition status of the wheat on plots with undersown fescue significantly affected wheat biomass production after anthesis. The global interception efficiency index IG epsilon(i) indicated that the fraction of the PAR(o) intercepted by the wheat during its growth (255 days) was 0.35. (C) 2009 Elsevier B.V. All rights reserved.
  • Authors:
    • Launay, M.
    • Tourdonnet, S. de
    • Shili-Touzi, I.
    • Dore, T.
  • Source: Field Crops Research
  • Volume: 116
  • Issue: 3
  • Year: 2010
  • Summary: The introduction of a living cover crop during a cash crop growth cycle (relay intercropping) and its maintenance after the cash crop harvest may help to preserve biodiversity, increase soil organic matter content and carbon sequestration and provide other ecosystem services, such as natural pest regulation or nutrient recycling, by increasing useful biotic interactions within the agroecosystem. We studied the impact of various approaches to manage a red fescue cover crop in a winter wheat crop in terms of light, water and nitrogen competition, using the STICS crop model adapted for intercropping. The STICS model for wheat/fescue intercropping was first evaluated on two years of experimental data obtained in the field. It gave satisfactory statistical results for the prediction of dry matter, leaf area index (LAI) and nitrogen accumulation in the two species, and for nitrogen and water dynamics in the soil. By simulating unmeasured variables, such as transpiration, the model improves our understanding of the performance of the intercrop in the field. For example, we showed that the intercropping system was more efficient that wheat grown as a sole crop, in terms of nitrogen accumulation and decreasing soil nitrogen levels before the leaching period. However, it also resulted in lower wheat yields. We then used the STICS model to compare four intercropping management scenarios differing in terms of the date of red fescue emergence, over 35 climatic years. We found that, in most climatic scenarios, the emergence of the fescue crop during the late tillering phase of the wheat crop gave the best compromise between wheat yield overall nitrogen accumulation and radiation interception.
  • Authors:
    • Walter, C.
    • Durand, P.
    • Viaud, V.
    • Sorel, L.
  • Source: Agricultural Systems
  • Volume: 103
  • Issue: 9
  • Year: 2010
  • Summary: Evaluating the environmental impacts of agricultural practices increasingly involves the use of spatially distributed simulation models that account for crop allocations across fields as an input factor. Our objective was to develop a model for spatio-temporal allocation of crops to a field pattern that was able to account for agronomic and spatial driving factors including crop production objectives, spatial distribution of the crops around farmsteads, and preferential allocation of crops on soil waterlogging classes. We developed a model based on stochastic decision trees (SDTs) to integrate farm type and field characteristics (area, distance to farmstead, waterlogging, and current crop) in the spatio-temporal allocation process without prior expert knowledge, and we compared the model to a reference model based on first-order Markov chains or transition matrices. A case study comparing both models was performed in the Naizin catchment (Western France), where crop allocation to fields was known for the period 1993-2006. The SDTs built had a general structure similar to transition matrices. SDTs and transition matrices exhibited similar performances in predicting crop transitions in time and in allocating crops to the proper soil waterlogging class. However, SDTs proved to better reproduce the spatial distribution of crops around the farmsteads. SDTs provide an integrated way to analyze and simulate crop allocation processes within a single integrated framework. The ease of constructing decision trees suggests potential couplings of SDT to various landscape-scale ecological models requiring a detailed description of the land use mosaic as input data. (C) 2010 Elsevier Ltd. All rights reserved.
  • Authors:
    • Scopel, E.
    • Triomphe, B.
    • Tourdonnet, S. de
    • de Tourdonnet, S.
  • Source: Proceedings of a symposium on Innovation and Sustainable Development in Agriculture and Food, Montpellier, France, 28 June to 1st July 2010
  • Year: 2010
  • Summary: No-tillage techniques and conservation agriculture (CA), based on minimal soil disturbance, the maintenance of plant cover and a diversification of rotations and intercropping, are developing rapidly in both the North and South. The emergence of these techniques often involves an original process of innovation based on continuous and adaptive learning within innovative socio-technical networks, which overturn the traditionally linear process of innovation design and transfer. Changes in the functioning of the agrosystem associated with CA are likely to supply ecosystem services, but the difficult implementation of these techniques may decrease the performance of the agrosystem, in particular by increasing dependence on pesticides. The general objective of the PEPITES project is to generate knowledge concerning ecological processes, technical and social innovation processes and their interactions, for the evaluation and design of more sustainable technical and support systems. We are working towards this objective by constructing an interdisciplinary approach combining biophysical sciences, cropping system and production system agronomy and the sociology of innovation, in partnership with professionals in four study terrains: conventional field crops in France, organic farming in France and small-scale family farms in Brazil and Madagascar. After one year of operation, we present here the progress made towards answering the questions posed in this project, in terms of the positioning of research with respect to two key questions: first concerning the construction of an interdisciplinary approach in partnership to assist the innovation process and the generation of knowledge, and second the construction of an approach for comparing terrains in the North and South.